Many political parties base their political action and program on an ideology. In social studies, a Political Ideology is a certain ethical set of ideals, principles, doctrines, myths or symbols of a social movement, institution, class, or large group that explains how society should work, and offers some political and cultural blueprint for a certain social order. A political ideology largely concerns itself with how to allocate power and to what ends it should be used. Some parties follow a certain ideology very closely, while others may take broad inspiration from a group of related ideologies without specifically embracing any one of them.

Political ideologies have two dimensions:

Goals: How society should work (or be arranged).

Methods: The most appropriate ways to achieve the ideal arrangement.

An ideology is a collection of ideas. Typically, each ideology contains certain ideas on what it considers to be the best form of government (e.g. democracy, theocracy, etc), and the best economic system (e.g. capitalism, socialism, etc). Sometimes the same word is used to identify both an ideology and one of its main ideas. For instance, "socialism" may refer to an economic system, or it may refer to an ideology which supports that economic system.

Ideologies also identify themselves by their position on the political spectrum (such as the left, the center or the right), though this is very often controversial. Finally, ideologies can be distinguished from political strategies (e.g. populism) and from single issues that a party may be built around (e.g. opposition to European integration or the legalization of marijuana). Philosopher Michael Oakeshott provides a good definition of ideology as "the formalized abridgment of the supposed sub-stratum of the rational truth contained in the tradition."

Studies of the concept of ideology itself (rather than specific ideologies) have been carried out under the name of systematic ideology.

There are many proposed methods for the classification of political ideologies. See the political spectrum article for a more in-depth discussion of these different methods (each of whom generates a specific political spectrum).